I woudn't give it to the folks who could easily afford it. Because if they don't care enough to forego a week of lattes to buy a seat for their child (SCARY that it could be that easy!) then they probably don't care enough to chip their nails on the buckle or properly install it and hurt their upholstery.
My boss is like this, and I have to accept it. Last week he got me all excited after two kids were killed in a car wreck here (that sounds wrong, doesn't it?) that he was buying new seats for ONE of his vehicles. He had me find the ones I thought he should get. Then he hemmed and hawed about how expensive they were (says a man whose wife gets twice weekly manicures, massages, etc and has herself three medium starbucks lattes a day) and eventually decided that the kids would be fine. A 2 and 3 year old. The two year old is in a turbo booster occasionally (with the shoulder belt tucked behind her back and the lap belt routed OVER the armrests) and the three year old is normally totally unrestrained. But, I have come to the conclusion that even if they HAD perfectly good seats, they wouldn't USE them. They have a summit INSTALLED IN THE CAR that the 2 year old fits in but they won't use (and an AO elite in the other car, same story) because she wants the booster. So she gets the ill use booster and the three year old rides in the middle, in the cargo hold, on the floor, wherever he wants to.
Even if someone gave them free seats, they probably wouldn't use them. Well, considering that their 3 year old knows how to properly buckle himself in and she tells him not to worry about it, I KNOW they wouldn't use them.